http://chroniclingamerica.loc.gov/search/pages/
Although it is not as user friendly as I'd like, it is useful and the search engine works fairly well. LSU Libraries is participating, and they are in the process of digitilizing several Louisiana newspapers. Thus far, they have portions of the extant issues of the "Ouachita Telegraph" available, plus several Natchitoches and Shreveport newspapers. There are also a handful of papers from smaller Louisiana towns. I presume that they have purposely not focused upon the New Orleans newspapers since other (for pay) sites have digitilized them. I'm not sure why there are not more papers from Baton Rouge. To see a list of available titles thus far, you can look here:
http://chroniclingamerica.loc.gov/newspapers/
Tim